JPH0452793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording medium. Specifically, the present invention relates to a thermal transfer recording medium that provides a good dye transfer image even on plain paper with low surface smoothness.

[Prior Art] A thermal transfer recording medium has been conventionally used as a recording medium for transferring and forming an image on a recording sheet such as plain paper by a thermal printer, a thermal facsimile, or the like. This thermal transfer recording medium has at least one coloring material layer on a support, and the coloring material layer includes, for example, a layer containing a coloring agent made of a dye such as a pigment and a heat-fusible substance. etc. are known. In addition, films with excellent surface smoothness and dimensional stability are used as the support in order to obtain good reproducibility of the dye transfer image obtained from the color material layer coated on the support. There is.

When these conventional thermal transfer recording media print on various types of paper ranging from paper with low smoothness to paper with high smoothness, they can print well on paper with high smoothness, but they print on paper with low smoothness. ``Fading'' occurs in the line drawing area, and in the case of so-called solid black, ``white spots'' occur.
appears and becomes very difficult to see. This is a major obstacle to the widespread use of thermal printers, and a solution is urgently needed.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and it is possible to perform good printing in a wide smoothness range from paper with high smoothness to paper with low smoothness. The technical challenge is to

[Means for Solving the Problems] A thermal transfer recording medium of the present invention for solving the above-mentioned technical problem is a thermal transfer recording medium having a heat-fusible coloring material layer on a support. It is characterized in that the material layer contains 10 to 60% by weight of dodecylbenzenesulfonate, which is a surfactant. The present invention will be explained in more detail below.

The heat-melting color material layer in the present invention mainly contains dodecylbenzenesulfonate as a surfactant, a heat-melting substance (a low melting point substance or a low softening point substance), a coloring agent, and a softening agent.

The method of incorporating the surfactant of the present invention into the heat-melting coloring material layer is arbitrary. For example, the surfactant may be incorporated into the heat-melting coloring material layer by dispersing it in the heat-melting coloring material layer, or by dissolving it in an appropriate solvent. It can be added as an additive.

The heat-melting substance used in the present invention is a solid or semi-solid substance with a melting point (measured value by Yanagimoto MPJ-2 model) or a softening point (measured value by ring and ball method) of 40 to 120°C, more preferably 60 to 120°C. It is a solid substance,
Specific examples include plant waxes such as carnauba wax, wood wax, auricilla wax, and esparto wax, animal waxes such as beeswax, insect wax, serrata wax, spermaceti wax, paraffin wax, microcrystalline wax, and esters. In addition to waxes such as petroleum waxes such as wax and oxidized wax, mineral waxes such as montan wax, ozokerite, and ceresin; higher fatty acids such as palmitic acid, stearic acid, margaric acid, and behenic acid; palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricial alcohol,
Higher alcohols such as eicosanol; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate, myricyl stearate; amides such as acetamide, propionic acid amide, palmitic acid amide, stearic acid amide, amide wax; ester gum, Rosin Rosin derivatives such as maleic acid resin, rosin phenolic resin, and hydrogenated rosin; Polymer compounds such as phenolic resin, terpene resin, cyclopentadiene resin, and aromatic resin; Higher amines such as stearylamine, behenylamine, and palmitic amine Examples include polyethylene oxides such as polyethylene glycol 4000 and polyethylene glycol 6000, and these may be used alone or in combination of two or more. Among these, higher amides such as palmitic acid amide, stearic acid amide, oleic acid amide, and amide wax are particularly preferred. Furthermore, the "thermofusible solid component that is solid at room temperature" described in JP-A-54-68253 and the "vehicle" described in JP-A-55-105579 may also be used. .

The low melting point substance used in the coloring material layer of the present invention is particularly preferably a combination of a hard wax and a soft wax (one type or two or more types of each). Hard wax [25℃
(100g) (according to JIS K2530)
Examples of waxes with a wax content of less than 8 include ester waxes (natural ester waxes such as carnauba wax and Montan wax, and waxes manufactured by Hoechst).
Hoechst Wax E, F, KP, KPS, BJ, OP,
synthetic ester waxes such as OM, X22, U and O), oxidized waxes (paraffin waxes,
Wax obtained by oxidizing wax such as microcrystalline wax, NPS manufactured by Nippon Seiro Co., Ltd.
-9210, NPS-6115, manufactured by Toyo Petrolite Co., Ltd.
PETRONABA・C, CARDIS314, etc.), low molecular weight polyethylene wax (especially molecular weight 300-1000)
Made by Toyo Petrolite Co., Ltd.
POLYWAX 500 and 655, etc.), acid waxes (Hoechst Wax S and LP, etc. manufactured by Hoechst), and the like. In addition, examples of soft waxes (waxes with a penetration rate (according to JIS K2530) of 8 or higher at 25°C (100g)) include microcrystalline waxes (Nisseki Microwax 155, 180 (manufactured by Nippon Oil Co., Ltd.)). ), HI-MIC-1080,
HI-MIC-2065, HI-MIC-2095, HI-MIC-
1070, HI-MIC-1045, HI-MIC-2045 (manufactured by Nippon Seirosha), STAR WAX100, BE
SQUARE175, 185, VICTORY,
ULTRAFLEX (manufactured by Toyo Petrolite Co., Ltd.), stearic acid, behenic acid, stearyl alcohol,
White wax, beeswax, dodecyl stearate, stearon, sorbitan monostearate, polyoxyethylene monostearate, or Diacarna
30 and Diakaruna PA30L (manufactured by Mitsubishi Kasei Corporation). In addition, when such hard wax and soft wax are used in combination, the weight ratio used may be 1:9 to 9:1 (more preferably 2:8 to 8:2).

The coloring agent to be contained in the color material layer of the present invention may be appropriately selected from dyes and pigments. Examples of the dye include direct dyes, acid dyes, basic dyes, disperse dyes, and oil-soluble dyes (oil-soluble metal complex salts). (including dyes), etc. These dyes may also be ballasted dyes. On the other hand, as the pigment, in addition to organic pigments such as phthalocyanine pigments, inorganic pigments such as carbon black can be used.

The coloring agent to be contained in the coloring material layer of the present invention is particularly preferably non-sublimable, and as a non-sublimating colorant, it can be transferred to a recording sheet such as plain paper together with a heat-fusible substance during heating recording. is possible,
Any non-sublimable substance that has a color may be used. Non-sublimable colorants preferably used in the present invention are colorants excluding sublimable (including those that vaporize with melting or dissolution) used in mordant dyes and the like.

Basic dyes preferably used as the colorant in the present invention include, for example, crystal violet (C.
Triphenylmethane dyes such as Malachite Green (CI42555), Malachite Green (CI42000), Methyl Violet (CI42535), Victoria Blue (CI44045), and Mazienta (CI42510), Auramine (C.
Diphenylmethane dyes such as I.655), Astraphloxin FF (CI48070), Eisenkathylon Yellow 3GLH (Hodogaya Chemical Co., Ltd. product, C.I.655), etc.
I.48055), Eisenkachironretsudo 6BH (C.
I.48020) Astrazone Golden Yellow GL
Methine and azamethine dyes such as (Bayer product, CI48054), Rhodamine B (CI45170),
Xanthene dyes such as Rhodamine 6G (CI45160), thiazole azo and triazole azo dyes such as Astrazone Blue GL (CI11052), Astrazon Red F3BL (CI11055), Eisencathilone Blue 5GH (CI11085), methylene blue ( Quinoneimine dyes such as CI52015), insulating azo dyes with an onium group at the structural end such as Eisenkathyron Red GTLH (CI11085), Ceblon Yellow 3RL (DuPont product, CI11087), Astrazone Blue FGL (CI61512), etc. Examples include anthraquinone dyes.

Examples of oil-soluble metal complex dyes include symmetrical 1:2 type azo metal complex dyes, asymmetrical 1:2 type azo metal complex dyes, 1:1 type azo metal complex dyes, azomethine metal complex dyes, and formazan type metal complex dyes. Examples include metal complex dyes, metal phthalocyanine dyes, and organic base salts of these dyes. Specifically, Eisenspiron Yellow 3RH (Hodogaya Chemical Co. product, CI Solvent Yellow 25), Zapon Fast Yellow R (BASF product, CI18690), Eisenspiron Orange 2RH (CI Solvent Orange 40), Zapon Fast Scarlet B (C.
I.12783), Eisenspiron Red GEH (CI Solvent Red 84), Zaponphastrone BE
(CI12715), Zapon Fast Violet BE (C.
I.12196), Cyanine Blue BB (Sumitomo Chemical Co., Ltd. product,
CI74160), Variable Asto Black #3804 (Orient Chemical Company product, CI12195), Eisenspiron Yellow 3RH Special (CI Solvent Yellow 25:1), Eisenspiron Orange 2RH Special (CI Solvent Orange 40:1), Eisenspiron Blue 2BNH (CI Solvent Blue 117), Zapon Fuasto Blue HFL (C.
I.74350), Eisenspiron Black BH Special (CI Solvent Black 22:1), etc.

Acidic dyes such as CI Acid Yellow
19, CI Assisted Red 37, CI Assisted Blue
62, CI Acid Orange 10, CI Acid Blue 83, CI Acid Black 01, etc.

Direct dyes are CI Direct Yellow 44, CI
Direct Yellow 142, CI Direct Yellow 12, CI Direct Blue 15, CI Direct Blue 25, CI Direct Blue 249, CI Direct Red 81, CI Direct Red 9, CI Direct Red 31, CI Direct Black 154,
Examples include CI Direct Black 17.

The disperse dyes are CI Dispose Yellow 5, C.
I. Dispose Yellow 51, CI Dispose Yellow 64, CI Dispose Red 43, CI Dispose Red 54, CI Dispose Red 135,
Examples include CI Dayspose Blue 56, CI Dayspose Blue 73, and CI Dayspose 91.

The ballasted dyes used in the present invention are dyes having at least one ballast group in the dye matrix, such as azo dyes, azomethine dyes, anthraquinone dyes, naphthoquinone dyes, sterine dyes, quinophthalo dyes, and phthalocyanine dyes. Ballast groups are groups that are highly soluble in heat-melting substances, such as alkyl groups, cycloalkyl groups, aralkyl groups, alkoxy groups, alkylsulfonylamino groups, alkylsulfonyl groups, hydroxylalkyl groups, cyanoalkyl groups, alkoxycarbonylalkyl groups,
It is a group having an alkyl group having 6 or more carbon atoms, such as an alkoxyalkyl group and an alkylthio group, or an alkylene group. In particular, a ballast group having at least one alkyl group having 6 or more carbon atoms in the molecule is preferred. As an example of the structure of the ballasted dye preferably used in the present invention,
Examples include those described in patent application (A) filed on the 25th, but the present invention is not limited thereto.

It is preferable that the color material layer of the present invention contains a softener. The softener used in the present invention preferably has a softening point (measured by the ring and ball method) of 40 to 200°C, and either hydrophilic or hydrophobic polymers can be used. Examples of hydrophilic polymers include gelatin, gelatin derivatives, cellulose derivatives, proteins such as casein, natural products and natural product derivatives such as polysaccharides such as starch, water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, and acrylamide polymers. Examples include synthetic water-soluble polymers such as polyvinyl compounds, vinyl-based and polyurethane-based polymer latexes, and the like. As a hydrophobic polymer,
U.S. Patent No. 3142586, U.S. Patent No. 3143386, U.S. Patent No. 3062674
Examples include synthetic polymers described in No. 3220844, No. 3287289, and No. 3411911. Preferred polymers include polyvinyl butyral, polyvinyl formal, polyethylene,
Cellulose derivatives such as polypropylene, polyamide, ethyl cellulose, cellulose acetate, polystyrene, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, ethylene-ethyl acrylate, ethylene-vinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate. Examples include maleic acid terpolymers, acrylic resins such as polymethyl methacrylate, polyisobutylene, rosin derivatives such as ester gum, petroleum resins, coumaron indene resins, cyclic rubbers, chlorinated rubbers, and the like. In the present invention, one or a combination of two or more of these softeners may be used.

Although the composition ratio of the coloring material layer of the present invention is not limited,
Total solid content of color material layer 100% (weight%, same below)
35 to 85% (more preferably 50 to 70%) of heat-melting substances, 5 to 20% of colorants, and 0 to 20% of softeners.
30% (more preferably 1 to 10%), and the surfactant of the present invention accounts for 10 to 60%, preferably 20 to 40%, of the solid weight of the hot-melt colorant layer.

If the amount of the surfactant of the present invention added exceeds 60%, cracks will occur in the coloring material layer during raw storage, and the film will peel off. On the other hand, if it is less than 10%, the effect is poor and the object of the present invention cannot be achieved. Conventionally, the heat-melt colorant layer contains 5% or less of a surfactant to improve the dispersibility of the colorant, but this amount is insufficient for printing on paper with low smoothness. Therefore, the effects of the present invention cannot be obtained. The effect of the surfactant used in the present invention is to create a strong affinity with polar components such as cellulose in the paper to be transferred, thereby strengthening the adhesion to the paper. Therefore, it differs from the conventional action of simply using it as a separating agent.

The color material layer of the present invention may contain various additives in addition to the above components. For example, castor oil,
Vegetable oils such as linseed oil, olive oil, animal oils such as whale oil and mineral oils may be suitably used.

The support used in the thermal transfer recording medium of the present invention preferably has heat-resistant strength, high dimensional stability, and high surface smoothness. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, coated paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, polyimide, paper-resin film composites, aluminum foil, etc. Metal sheets and the like are preferably used. The thickness of the support is preferably about 60 .mu.m or less, particularly 2 to 20 .mu.m, in order to obtain good thermal conductivity. Furthermore, in the thermal transfer recording medium of the present invention, the structure on the back side of the support may be optional, and a backing layer such as a sticking prevention layer may be provided.

In the heat-sensitive transfer recording medium of the present invention, techniques suitable for applying the heat-melting coloring material layer to a support such as a polymer film are known in the art, and these known techniques are also applicable to the present invention. can. For example, the hot-melt coloring material layer is a layer formed by hot-melt coating the composition or by solvent coating a coating solution prepared by dissolving or dispersing the composition in an appropriate solvent. As a method for applying the heat-melting color material layer of the present invention, any technique such as a reverse roll coater method, an extrusion coater method, a gravure coater method, a wire bar coating method, etc. can be adopted. The heat-melting coloring material layer of the present invention is 20 μm thick.
Hereinafter, the thickness may be more preferably 1 to 15 μm.

The thermal transfer recording medium of the present invention may contain highly thermally conductive fine powder in its constituent layers and/or in its support. The high thermal conductivity fine powder has a higher thermal conductivity than the above-mentioned softener (for example, the thermal conductivity
6.0×10 ^-4 ~25.0×10 ^-4 cal/sec・cm・℃) and has a high melting point. Many metals such as aluminum and copper can be used, and tin oxide,
Oxides such as aluminum oxide and magnesium oxide, and nitrides such as titanium nitride can also be used. The particle size of the high thermal conductivity fine powder of the present invention is preferably 3 μm or less, more preferably 1 μm or less.

The thermal transfer recording medium of the present invention has other constituent layers such as an undercoat layer (for example, a layer for improving film adhesion), an intermediate layer, and an overcoat layer (for example, a layer made of a heat-melting substance). You can leave it there.

[Function] The thermal transfer recording medium of the present invention can be recorded (printed) on transfer paper such as plain paper by the same method as known thermal transfer recording media, and can print well even on paper with low smoothness. It becomes possible to do this. Although the reason is not necessarily clear, it is inferred as follows. That is, for example, the colorant layer is dissolved by heating with a thermal head according to the image information, but at this time, due to the action of the surfactant, the colorant after heating and melting dissolves into polar groups on the surface of the transfer paper (e.g. It is thought that the adhesion force is strengthened by interaction with hydroxyl groups, carboxyl groups, etc.).

[Effects of the Invention] According to the present invention, in a heat-sensitive transfer recording medium in which a heat-melting coloring material layer is laminated on a support, the heat-melting coloring material layer contains 10 to 60% by weight of a surfactant. With this structure, the above-mentioned technical problem of the present invention can be solved by a simple means of using a surfactant in the heat-melting coloring material layer.

[Example] Examples are given below, but the embodiments of the present invention are not limited thereto. Note that "parts" used below indicate "parts by weight."

Example 1 A heat-fusible colorant layer coating solution having the following composition was applied onto a 5.3 μm thick polyethylene terephthalate film using a wire bar.

Colorant layer coating liquid Carbon Black 10 parts Microcrystalline wax (Micro
UHF BARECO Co., Ltd.) (melting point 62℃) 20 parts Montan wax (Kato Yoko Co., Ltd.) (melting point 80℃)
20 parts ethylene-ethyl acrylate resin (NUC-
6070 (manufactured by Nippon Unicar Co., Ltd.) 2 parts Sodium dodecylbenzenesulfonate 10 parts Toluene 120 parts After coating, drying was performed at 40°C to obtain a thermal transfer recording medium sample of the present invention. The dry film thickness was approximately 4 μm.

Using this thermal transfer recording medium sample, a thermal printer (prototype machine equipped with a thin-film line thermal head with a heating element density of 8 dots/mm) was used to apply power per heating element of 0.9 W and application time. Recording was performed by applying energy for 2 milliseconds. Bond paper (Beck smoothness 12) is used as transfer paper.
seconds) was used. As a result, line drawings appear blurry.
Clear printing was obtained with no "white spots" occurring in solid black areas.

Example 2 In Example 1, a heat-fusible colorant layer coating solution having the same composition as the sample was used except that sodium dodecylbenzenesulfonate was changed to 55 parts. The film thickness after drying at 40°C was approximately 4 μm. Printing was carried out in the same manner as in Example 1 using this thermal transfer recording medium sample of the present invention. As a result, clear printing was obtained with no "fading" in the line drawings and no "white spots" in the solid black areas.

Comparative Example 1 In Example 1, a heat-melting coloring material layer coating solution having the same composition as the sample was used except that 5 parts of sodium dodecylbenzenesulfonate was used. The film thickness after drying at 40°C was approximately 4 μm. Printing was carried out in the same manner as in Example 1 using this comparative thermal transfer recording medium sample, but "fading" occurred in the line drawing areas and "white spots" appeared in the solid black areas, resulting in very hard to read prints. Ta.

Comparative Example 2 In Example 1, a heat-fusible colorant layer coating solution having the same composition as the sample was used except that sodium dodecylbenzenesulfonate was changed to 65 parts. The film thickness after drying at 40°C was approximately 4 μm. When this comparative thermal transfer recording medium sample was left at 40° C. for two weeks, cracks appeared in the coloring material layer and peeling occurred. Incidentally, although the samples ~ were left under the same conditions, this problem did not occur with any of the samples.

Claims (1)

[Claims] 1. In a heat-sensitive transfer recording medium having a heat-melting coloring material layer on a support, the heat-melting coloring material layer has a thickness of 10 to 60
1. A heat-sensitive transfer recording medium comprising a heat-melting material layer containing % by weight of dodecylbenzenesulfonate.